1. Field of the Invention
This invention relates to cargo-handling apparatus for use with adjustable spreaders on container handling shore cranes. More particularly, the invention relates to an apparatus used to connect an adjustable auxiliary frame to an adjustable shore crane spreader wherein the auxiliary frame is of the type that can be used with containers having overheight cargo.
2. Discussion of the Prior Art
The use of intermodal containers has enabled shippers to realize great savings in time and labor in handling cargo. As the industry has evolved, so has the development of specialized apparatus for handling containers. The most dramatic development has been the evolution of the shore crane with adjustable spreaders designed specifically for rapid handling of various sizes of intermodal containers.
Not all cargo is sized such that it will fit within the confines of the standard size containers. Frequently, flat bed or open-topped containers must be used with cargo that will extend beyond the top of the container making it impossible to use the standard shore crane spreaders.
The original method for handling these overheight containers is by connecting wire rope slings, commonly referred to as "emergency gear". This gear consists of four independent wire ropes, each with a shackle at one end for connecting to padeyes on the spreader and a twist lock device for connecting into the container corner lifting fitting. This method is highly labor intensive and consumes valuable dockside time. Also, this method is considered hazardous since it requires that personnel climb to the top of the container to attach the twist lock devices into the container lifting fittings and to disengage the same after handling the container.
Overheight containers can only be carried in two positions on the vessel--either on the top tier below deck or on the top tier above deck. For this reason, these loads are normally handled only one to three at a time.
One device illustrated in U.S. Pat. No. 3,829,145 for handling overheight cargo, utilizes an extension frame which is pinned to the spreader. This frame is transported to and from the shore crane by a separate carrier such as a flat bed tractor-trailer rig. The connection of the spreader to the frame is made by manually inserting (4) pins into padeyes on both the spreader and the extension frame. Once the spreader is pinned to the frame, the spreader twist locks operate similar twist locks on the bottom of the frame through torque tubes in the corner posts of the extension frame. This frame is made either fixed in length or adjustable in length for use with expandable spreaders. The disadvantage with this system is that, unless more than four or five overheight containers are to be used, it is too labor intensive to justify its use. In addition, a separate piece of equipment is required to store the frame when not in use.
An improvement in the above-mentioned method comprises having the extension frame stored on the shore crane whereby the crane spreader is landed on the frame, spreader twist locks are locked, which also locks the frame twist locks, the spreader and frame are then hoisted and lowered to the dock to allow a separate set of twist locks to be manually activated to lock the spreader to the frame. Due to mechanical safety interlocks, the spreader twist locks cannot be unlocked unless the spreader and frame are seated firmly on a container or a special pad which will allow the spreader and frame to land with twist locks locked or unlocked. Once the auxiliary twist locks have been locked at dock level, the spreader and frame must be returned to the stored position on the crane which has a specially built pad to allow the main twist locks to be unlocked. At that time the spreader and frame can be used to handle containers with overheight loads. To disengage the frame, the spreader and frame must be returned to the stored position, main twist locks locked, then the spreader with frame must travel to dock level to allow manual unlocking of the auxiliary twist locks. Once this is done, the spreader carries the extension back to the stored position, unlocks the main twist locks, then travels free to return to handling containers. While not labor intensive, this development of the overweight spreader extension frame requires numerous extra moves between dock and the frame's stored position, resulting in excessive lost time.
To date, the result of considerable effort has not produced an apparatus which meets all of the necessary criteria. The present invention therefore fulfills the container shipping industry needs by providing an effective, easy-to-use, and efficient apparatus for handling containers with overheight loads.